1. Field of the Invention
The present invention relates to the terminal structure of a direct electric current (DC) superconducting cable and to a DC superconducting cable line.
2. Description of the Related Art
The superconductor of a superconducting cable is generally constituted by a superconducting layer which is formed by spirally winding superconducting wires around a core material (hereinafter called a “former”). When the superconducting cable is used as a direct electric current cable, soldering is generally performed for connecting superconductors together or connecting the end of a superconductor with a wire consisting of a normal conductor (for example, refer to Japanese Patent Application Publication No. 10-228933). Some of superconducting cables have a multilayer structure superconductor consisting of a plurality of superconducting layers (for example, see FIG. 3 of Japanese Patent Application Publication No. 10-228933). In this case, as shown in FIG. 3 of the 10-228933 gazette, soldering is done simultaneously such that the ends of all superconducting layers conduct to each other.
In a DC power transmission and distribution system which is constituted by a plurality of power supplies and loads, a plurality of cables are connected to the respective power supplies so as to form a plurality of circuits, which results in increase in the number of cables to be used. In this case, it is possible to increase the amount of electric current and to decrease loss by using superconducting cables. However, a number of cables must be used according to the number of the power supplies, and the space for arranging the cable distribution line is necessary.